CGAL users discussion list

["Sebastien Loriot (GeometryFactory)" <>]

On 07/26/2012 09:09 AM, Marc Mörig wrote:
> Dear CGAL maintainers,
>
> in the file Sqrt_extension_type.h, there is the following code:
>
> std::pair<double, double> compute_to_interval() const
> {
> if (! is_extended_)
> return CGAL_NTS to_interval(a0_);
> CGAL::Interval_nt<false>::Protector p;
> const CGAL::Interval_nt<false>& a0_int = CGAL_NTS to_interval(a0_);
> const CGAL::Interval_nt<false>& a1_int = CGAL_NTS to_interval(a1_);
> const CGAL::Interval_nt<false>& root_int = CGAL_NTS to_interval(root_);
> const CGAL::Interval_nt<false>& x_int =
> a0_int + (a1_int * CGAL::sqrt(root_int));
>
> std::pair<double, double> res(x_int.inf(), x_int.sup());
> this->update_cached_value(res);
> return res;
> }
>
>
> The Protector p sets a directed rounding mode for floating point
> arithmetic, which is propagated to other code inside, e.g.
> to_interval(a0_). In my case, this breaks code which assumes the default
> rounding mode.
Are you sure the problems is coming from that part? The previous
rounding mode mode is restored when the protector is deleted.

Sebastien.


> Should I consider this a bug or a feature? It is easily fixable in CGAL
> though.
>
> Regards,
> Marc Mörig